Experiments are proposed to study the chemistry and metabolism of lipids in the retina and related tissues. The role of essential fatty acids in the function of the rod visual cell will be investigated. Detailed chemical analyses of the neutral lipids and phospholipids of several vertebrate and invertebrate species will be carried out. The mechanism of renewal of lipids in rod outer segments will be determined. The metabolism of fatty acids, neutral lipids, and phospholipids will be studied in whole retina, rod outer segments, and the pigment epithelium. These studies should provide valuable information on the role of lipids in photoreceptor structure and function.